Coupling device



P 0, 1946. A. J. BIELSKI ET AL COUPLING DEVICE Filed Sept. 7, 1942 Patented Sept. 10, 1946 Wayne, Ind., assignors to Farnsworth Television and Radio Corporation, a corporation of Delaware 1 hpplication September 7, 1942, Serial No. 457,548

. 1 This invention pertains generally to radio frequency communication circuits and more par.- ticularly to a device for couplingsuch circuits to a coaxial cable transmission'line.

- Conventional high-frequency radio communication circuitsinclude various types of coupling devices for inductively and capacitively coupling vacuum tube circuits to coaxial cables. Difiiculty' has been experienced in providing coupling structure such that an eff cient ground i provided for the outer conductor of a coaxial cable.

3 Claims. (01. 178-44) If an efficient ground is not provided there occurs, I

in high-frequency radio circuits, excessive radiation of energy and interference with adjacent radio energy receivers. Furthermore; difficulty has been experienced in providing an easily adjustable coupling device for accurately obtaining an exact degree of coupling between vacuum tube circuits and the coaxial cable. Even though adjustable coupling devices are known, none has as yet been provided which is so constructed that its adjustment can be maintained despite serious Vibration. I

One well known adjustable coupling device includes a pair of plate members. one of which is fixed with relation to an axial conductor of a coaxial cable and the other of which may be variably spaced from the axial conductor by means of anarrangement of gears adapted to be manu ally operated. This arrangement is inherently expensive to build and it isdifiicult to provide an eificient' groundior th'e outer conductor of the coaxial cable." W1 V V The principal obj ct of this invention is to provide, in a high-frequency radio communication circuit, a coupling device particularly adapted for use with coaxial cable.

A further object of this invention is to provide, in a high-frequency radio communication circuit, a coupling device which is easily adjustable to an exact degree and which maintains its adjustment despite the eiiects of excessive vibration.

A still further object of this invention is to provide, in a high-frequency radio communication circuit, a coupling device particularly adapted to provide an effective ground connection to a coaxial cable and which is inexpensive to con-,

struct.

In accordance with this invention, there is provided an adjustable coupling device particularly 7 after.

'member is threaded to receive a cylindrical shield which may be rotated to either completely enclose the slotted member or partially and exactly expose the slot and the axial conductor to a variable degree to thereby vary the coupling between the axial conductor and the output circuit of a vacuum tube. The slotted member is split and internally threaded to receive a threaded plug which,rwhen tightened, may spread the slotted member into tight engagement with the shield to thereby prevent change of adjustment. For a better understanding of the invention, together with other and further objects thereof, reference is had to the following description, taken in connection with the accompanying drawing, and its scope will be pointed out in the appended. claims. In the accompanying drawing, Fig. 1 shows a plan view partly in section, of the coupling device provided in accordance with this invention.

Fig. 2 is an end view of Fig. 1 from the direction indicated by arrows 2-2 in Fig, 1.

'Fig. 3 isa cross-section on line 3-3 of Fig. 1.

Fig. 4 is an end view of Fig. 1 from the direction indicated by arrows 4 -4 in Fig. 1. 1 Referring particularly to Fig. 1 of the drawing'; there is shown a coupling member constructed in accordance with this invention, comprising a non-magneticsplit base member I which is adapted to be secured to a chassis such as is customarily provided in radio apparatus, and to clamp the outer conductor of a coaxial cable. A slotted non-magnetic stud 2 is secured by the bolts 3 to base I and the slotted stud clamps the turned-over edges 5 of the outer conductor 4 of a coaxial cable to the base I. The inner or axial conductor 6 of the coaxial cable extends through the base I into stud 2 as illustrated in the drawing, There is provided in stud 2 a slot 1 for exposing conductor 6 as will be described herein- Stud 2 is threaded at 8 to receive the non-magnetic shield III which is also threaded to provide an exact and easily adjustable means for enclosing the stud 2 and the inner conductor 6 of the coaxial cable to whatever degree is desired in the particular radio circuit in which the device is to be utilized. Shield I0 is slotted as shown at l2 in Figs. 1 and 2 wherebyit may be adjusted by means of a screw driver. There is also provided an opening l3 in shield l0 which provides access to a tapered screw threaded lock-.

i with the shield ii).

nut it: which is in threaded engagement with the stud 2. The locknut l 5, when tightened to a certain degree, spread the stud 2 by reason of the fact that it is split into sectors [1, as shown in Fig. 3, thereby to provide a vibration-proof adjustment between the shield Iii and stud 2, All of the parts described above may be constructed of brass, for example.

There is also shown in Fig. 1, the output of a vacuum tube circuit comprising a coil 20 and an adjustable condenser 2| which may be positioned in energy-transferring relation to the axial conductor 6. This circuit is shown by way of example only, as it will be obvious to those skilled in the art, that other forms of output circuits may also be utilized in connection with a coupling device of the nature disclosed herein.

This invention provides a very efiicient coupling device for use in ultra high-frequency circuits for the reason that base member I may be m unted secur y t the chas s o radio ai pflrfl l The chassis is customa ilytkep at ro nd p tential and, therefore, the end Of the coaxial cable adjacent the coupling member .is provided with a very wefi 'Qient ground such as indicated at 13 in i y providing such a groun the potential between the outer conductor 4 and ground, is maintained at vavery low value where-.-

by radiation of energy jfrcmthe cable is reduced to a minimum- The coupling between the axial conductor 5 and .coil 20, may be .varied by rotating shield L9 to Partially enclose or expose the axial conductor 6 and permit only a predetermined-flow of flux between the axial conductor and coil 20. Thus, there is obtained a desired degree-Of coupling. When the shield has once been ,adjusted to the desired position, the locknut 45 may berOtated tc impart lateral force tothesectors ill-of stud 2 whereby they spread into positive engagement This creates a considerable amount of friction between the stud 2 and the shield lil whereby its position cannot change under the effects orvibration.

It is not intended that this-invention shall be limited to use with arcoaxiaicable since it will be obvious to those skilled in the art that other forms of conductors may beconnected with a coupling device constructed in accordance with i this invention. However, this invention does pro videa very efiicient ground for coaxial cable circuits.

4 While there has been described What is at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes ,and'modifications as fall Within the true spirit and scope of the invention.

What is claimed is:

1. A coupling device for use in connection with an electrical conductor comprising a base, a slottedstudsecured .at one end to said base for receivingsaid conductor and exposing it to an electrical field the other end of said stud being surrounding saidstud and threaded thereto to provide for adjustment of said shield whereby to variably shield said inner conductor from said field, and means forspreading saidsectors whereby said shield may be locked to said. stud.

,3. -A coupling device for usein connection with a coaxial cable comprising a base member adapted to clamp to the outerconductor of said ,cable, a slotted stud secured at oneend to said base for clamping the turned-over-end of said outer conductor to said base and receiving the inner conductorof said coaxial-cableto-expose it to an electrical-field, the :otherend'of said stud being split into sectors, -a cylindrical, "nonmagnetic shield surrounding said stud and threaded thereto acent said sectors to provide for "adjustrnent of said shield whereby to-variably shield said innerconductol from said field anda tapered locknut threaded into-said other end of said stud whereby saidshield may be locked to said stud-whenisaid iocknut is tightenedrto spread the sectors of saidstud.

WAYNE J. 'LUCKOCK. ALEX J. BIELSKI. 

